There exist a large number of electromagnetic injection valves for the purpose of fuel injection into the suction pipe of combustion motors. A common characteristic for these injection valves is a desire for high dosage accuracy. Such high dosage accuracies can be achieved only with very short opening and closing times. Opening and closing times for the best known valves are 0.5-1.5 ms, depending somewhat on the impedance of the electromagnet. The required short closing times should be achieved with the lowest possible input of electrical decreased by armature bounce.
State of the art valves typically are of axially symmetric design. The armature of such valves is located at the central axis of the valve and acts on a valve obturator which in most cases is of needle-type design. Magnetic return flow usually is achieved by means of a metallic housing which includes both the magnet pole and the valve seat. The external diameter of such valves is typically 20-25 mm. The moving mass of the armature is typically from 1-4 g. In order to prevent objectionable armature bounce, and in order to achieve short floating times, the conventional injectors feature only very small stroke heights. The stroke heights of modern injector valves are in the range of 0.05-0.1 mm. In order to prevent unacceptable variations in flow-through characteristics, the state of the art valves require extremely tight machining tolerances. In addition, state of the art valves require a difficult calibration procedure.
It is the objective of this invention to define a very fast fuel injector with low armature bounce and low electric energy consumption requirements.